Group ii metal salts of a mixture of simple diesters of dithiophosphoric acids



No Drawing. Application October 12, 1951 Serial No.251,139

11 Claims. 0. 260-4299 This invention relates to new compositions of matter,

and more particularly pertains to novel, oil-soluble, di-

thiophosphate materials which include particularly the dlthiophosphoric acid di-esters and the salts derived from them.

At present it is known that dithiophosphoric acid di-.

esters (hereinafter designated as dithiophosphate acidesters") can be produced by reacting a-hydroxy compound such as an aliphatic alcohol with P 5 inappropriate relative amounts. The resultant product maybe further reacted with a salt-forming reagent, to produce a dithiophosphate salt-ester. These salt-esters can be used for a variety ofpurposes, but one main use is in lubricating oils. For this purpose, it is required that the saltester be permanently oil-soluble, and generally, since it is known that the organic radicle must have a sufficient number of carbon atoms in order to have an oil-solubilizing elfect, it willbe found that these salt-estersare usually prepared from high molecular weight hydroxy com- I pounds such aslong chain aliphatic alcohols and alkylsubstituted cycloaliphatic alcohols.

The amount of dithiophosphate salt-esters used for lubricant improvement purposes is very substantial. As a result, it is desired to produce these materials as cheaply as possible. Various prior art workers have conducted extensive research programs in an effort to reduce the cost of effective salt-esters, and recent developments emphasize decreasing the molecular weight of the organic substituents in the salt-ester to the permissible limit governed by oil solubility considerations. This technique at first glance appears plausible, because the high molecular weight hydroxy compounds are costly, and by using lower molecular weight hydroxy compounds, the cost might be reduced to a more attractive level.

This technique has been tried by me to the extent of reducing the number of carbon atom'sin the organic substituents in the salt-ester to six. Obviously the cost of manufacturing such materials is less; but unfortunately certain of such materials do not have satisfactorily permanent solubility in a variety of mineral lubricating oils as indicated by sedimentation after long periods of standing. This sedimentation was even more pronounced as the molecular weight of the substituent was further decreased, and in some cases, the material was initially oil-'- insoluble in substantially all proportions. After continued and prolonged investigation, it was quite unexpectedly discovered in accordance withthe present invention that exceptionally stable oil-soluble salt-ester materials could be produced by having present in the ma- 7 novel, stable, oil-soluble dithi-ophosphate salt-ester mate-.

I Patented June 10,

suited as corrosion and oxidation inhibitors inlubricatirig' oils. After having unexpectedly found thatstable, oilsoluble salt-esters could be economically produced in this novel way, another program was conducted to determine the effectiveness of the new salt-ester materials'as'cor-y economical to produce and are also more efiective than the heretofore known oil-soluble salt-esters i as corrosion inhibitors in lubricants, on a given weight basis. It is therefore'an object of the prescnt'invention to pro vide novel, stable, oilasoluble dithiophosphate salt-ester materials. Y f. 7

Another object of the present invention is 'to "provide bonatomsf 1 Y i Other objects of the present inventicnwill be apparent rials'whic'h containaliphatic radicals of less than caras the description proceeds.

In its broadest sense, the present inventionis concerned with novel compositions of matter comprising an 'oilsoluble organicdithiophosphate material, in which mate- I rial there is present a substantial proportion of eachof:

' dithiophosphate includes generically the dithiophosphora terial a substantial proportion of each of: (1) radicals Oil-soluble dithiophosphate salt-esters particularly selected from the class ic acid di-estersand the salts derived fromthem. Like Wise by the word material.it is meant'to include a a singlemixed compound, i. e. one in which'the two organic substituents attached to the same phosphorus atom-are different; (b) amixture of different simple compounds; i. e. compoundsfin which the two organic substituents attachedtotheqsame phosphorus atom are the same; (c) a mixture of one or more simple compoundsfwith one or more mixed compounds; (d) complex salt-compounds in which the radicals derived from two or more dissimilar dithiophosphoric acid di-esters are attached to a single divalent metal; and (2) mixtures of complex salts, or at least one complex salt in admixture with 'anyof the compounds under"(a), (b), and (0) above;

More specifically, the present invention is concerned with novel compositions of matter comprising an oilsoluble material consisting of at least one-compound hav iug the formula I in which R is a hydrocarbon radical selected from,.the.' class consisting of alkyl and cycle-alkyl radicalsyR'is an organic radical which may be the same as R, and X is selected from the group consisting of hydrogen'and one equivalent of a salt-forming element or radical;-an'd in which material there is a substantial proportion each of:

(a) alkyl radicals having less than 6 carbon atoms, and

(b) hydrocarbon radicals having at least six carbon atoms consisting of alkyl landcycloalkyl radicals. v i

The organic dithiophosphate material in-generalWill preferably contain from about 10. to about '9 O%}-of ali-. phatic hydrocarbonsubstituents having less -than'is'ix carbon atoms and. from, a

radicals selected from the class consisting of aliphatic and cycloaliphatic hydrocarbon radicals having at least carbon atoms. QMore usually,- thematerial ;will contam from about 30 to about 50% of radicals having less than six carbon atoms and from, about 70 to 50% of radicals having at least six carbon atoms. When, the

dithiophosphatematerials of the present invention are used. as lubricant additives, best results will usually be secured when, the average number of carbon atoms per phosphorus atom is in the range of from 8 to 9.6.

The mixed compounds can be illustrated by the fol-,

lowing structural formula:

(lauryl) dithiophosphate, cadmium (isopropyl) (4-meth-' yl-pentyl-2) dithiophosphate, magnesium (amyl) (hexyl) dithiophosphate; mercuric (isobutyl) (amyl-cyclohexyl) dithiophosphate, calcium (sec-butyl) (nonyl) dithiophosphate, barium (isopropyl) (capryl) dithiophosphate, strontium (ethyl) (octadecyl) dithiophosphate, magnesium (isoamyl) (heptyl) dithiophosphate, cadmium (iso-. propyl) (decyl) dithiophosphate, mercuric (sec-butyl) ('eicosyl) dithiophosphate, calcium. (propyl) (heneicosyl) dithiophosphate, zinc (ethyl) (docosyl) dithiophosphate, barium (sec butyl) (tricosyl) dithiophosphate, calcium (isopropyl) (lauryl) dithiophosphate, cadmium (isobutyl) (cetyl) dithiophosphate, etc.

Another dithiophosphate material involves a mixture of simple compounds in which from about 10 to 90% of the simple compounds contain less than twelve carbon bout. 90 to about 10%. of,

Thecomplex saltv compounds can be derived from simple compounds and/or mixed compounds. This is readily possible because the. dithiophosphate acid esters are monovalent, whereas the metallic radicals of this invention are divalent. These complex salt compounds can be used alone or in admixture with mixed compounds,single compounds or mixtures of mixed and single compounds. The complex salt compounds can be best illustrated by the following general formula:

wherein the hydrocarbon radicals in at least one configuration areditferent from those in a second such configuration, M is a divalent metallic radical. Examples of such complex salts are: Calcium di-isopropyl dithiophosphate-di-hexyl dithiophosphate, barium-di-butyl dithiopho'sphate-di-capryl dithiophosphate, magnesium-diethyl dithiophosphate-di-(methyl-cyclohexyl) dithiophosphate, strontium-di-amyl dithiophosphate-di-lauryl dithiophosphate, mixture of zinc-di-isop ropyl dithiophosphate-di-sec. butyl dithiophosphate and cadmium-di-nonyl dithiophosphate-di-cyclohexyl dithiophosphate, cadmiumdi-decyl dithiophosphate-di-amyl dithiophosphate, strontium-di-(propylcyclohexyl) dithiophosphate-di-isopropyl dithiophosphate, zinc-di-cetyl dithiophosphatedi-propyl dithiophosphate, zinc dice'ryl dithiophosphate-di-ethyl di- H thiophosphate; barium-di-eicosyl dithiophosphate-di-isopropyl dithiophosphate, barium-di-ethyl dithiophosphatedi-nonyl dithiophosphate, and calcium-di-methyl dithio phosphate-di-(ethyl-cyclohexyl) dithiophosphate.

Another dithiophosphate material which can be used is comprised of mixtures of one or more simple compounds and one or more mixed compounds or mixtures of mixed'compounds. The following table of specific examples illustrates this concept.

. atoms and from about 10 to 90% contain at least twelve Table II carbon atoms. Examples of such mixtures are illustrated in the following table:

' Table 1 Per- Per- Ex. Simple compounds. centage Mixed compounds centage No. of of Dithiophosphate salt Dithiophosphate salt radicals radicals Ex. esters wherein each Peresters wherein each Per- No. ofthe hydrocarbon centof the hydrocarbon centradicals contains at age of radicals containsless age of 1..-" zinedi-(hexyl-cyclo- Zmc (ethyl) (propyl) 45 leastficarbon atoms. radicals thanficarbon atoms. radicals hgiqgl) dithlophosdithiophosphate, p a e.

' 55 2 Zinc di-lauryl dithio- 20 Barium (nonyl) 45 1 Zinc dl-capryl dithio- Zinc di-isopropyl di- 40 phosphate. (octyl) dithiophosphate. thiophosphate. phosphate. 2 Calcium di-(methyl- Calcium di-butyl di- 35 3..." Strontium dr-amyl. 30, Calc1um(decyl) cyelohexyl) dithiothiophosphate. dithiophosphate (ethyl) dithiophosphate. phosphate 3 Magnesium di-hexyl 70 Strontium di-amyl di- 30 4.-." Magnesium di- 60 Cadmium (propyl) I 40 dithiophosphate. thiophosphate. (methylcyclohexyl) (butyl) dithiophos- 4 Cadmium di-heptyl 55 Calcium di-ethyl di- 45 6O dithiophosphate. phate.

dithiophosphate. thiophosphate. 5.. Cadmium di-butyl 47 Calcium (isopropyl- 53 5 Cadmium di-nonyldi- 50 Barium (ii-propyl di- 50 dithiophosphate. cyclohexyl) (6100' thiophosphate. thiophosphate. syl) dithiophos- 6 Zinc di-decyl dithio- 53 Magnesium di-sec. 47 phate.

phosphate. butyl dithiophos- 6-. Zinc di-eapryl dithio- 30 Mercuric (amyl-eyclo' 33 phate. phosphate. hexyl) (methyl- 7 Strontium di-lauryl 68 Zinc di-propyl dithio- 32 5 V cyclohexyl) dithiodithiophosphate. phosphate. 6 phosphate. 3 Barium di-(butyl-cy- 63 Zinc di-amyl dithio- 37 7 Magnesium di-lsopro- 43 Banum (hexyl) (hep- 57 clohexyl) dithiophosphate. pyl dithiophostyl) dlthiophosphosphate. phate. phate, 9 Cadmium di-hexyl di- 40 Barium di-isopropyl 2O 8 Cadmium di-lauryl 68 Strontium (ethyl) 32 thiophosphate. dithiophosphate. dithiophosphate. (amyl) dithiophos- Zinc di-(methyl-cyclo- 25 Zinc di-butyl dithio- 15 phate.

hexyl). phosphate. 70 9 Zinc di-ethyl dithio- 50 Zinc (cyclohexyl) 50 Mercuric di-(amyl-ey- 35 do 15 phosphate. (cetyl) dithiophoscloxyl) dithiophospate. 10 phate. y i Calcium di-isopropyl 21. Barium (cetyl) (ceryl) 32 Strontium di-eicosyl 35' Zinc di-amyl dithio- V 15 10..-- dithiophosphate. dithlophosphate.

dithiophosphate, phosphate. v Zinc di-butyl dithio- 10 Calcium (eicosyl) 37 11 Calcium di-lauryl di- 60 Calcium di-ethyl di- :40 phosphate.- (nonyl) dithiophosthiophosphate; thiophosphate. V y phate:

'5 The'preparation of the dithiophosphate salt-ester material is accomplished by 'at least one of the following methods:

basic reagent, followed by mixing the desired salts to-' gether;

(4) The mixed acids of method (1) above are mixed with the simple acids of method (2) above, and rthenithe resultant mixture is reacted with the desired reagent; and

The simple salts of method (3) above are mixed with the mixed salts 'of methods (1) above.

The methods"(l) and (2) above are preferred from a commercial standpoint because such methods require less equipment and the preparation of high molecular weight salts in situ with low molecular weight salts yields homogeneous liquid products.

There are available at least two processes by which the dithiophosphate acid esters are prepared, namely the Having the. theoretical acid number, the apptoximate percentage of dithiophosphate acid ester which is present in the product is determined by taking the-actual acid number of the product and dividing it by the theoretical acid number and then multiplying by 100. This percentage value is for convenience termed hereinafter as the conversion value. This conversion value is approximate and not the exact figure, because of small amounts of acidic by-products formed, dissolved H 5 and/or P 8 The conversion value can be as low as 5 by stopping the reaction in a short time, but usually it will be in the order of about 70 to 100, when using the preferred relative amounts of reactants, namely about 410 5 moles of alcoholic reactant and 1 mole of P 8 permitting the reaction to go to substantial completion.

In preparing the salts of the dithiophosphate acid esters, a salt forming material is reacted with (a) a mixed acid, or (b) a mixture of two or more simple acids,

batch process and the circulatory process. While I shall set forth in detail how each of said two processes may be carried out, I do this only for purpose of illustration and do not intend that my invention should be limited thereby. Any other suitable methods for the production of dithiophosphoric acid di-esters can be employed if it is so desired.

In the batch process, about 3 to 6 moles, preferably about 4 to 5 moles of an alcohol are placed in a reaction vessel equipped with a stirring device, and one mole of finely divided P 8 is added. The mixture is stirred for about one to six hours at about 40 to 100 C. At the end of the reaction period, the product may be decanted, filtered, or centrifuged to remove-any solid or unreacted materials which may be present.

In the circulatory process, the desired alcohol or mixture of alcohols is heated, for example, with a heat exchanger to a temperature of about 40 to 100 C., and then circulated or passed to a reaction chamber filledwith small lumps of P 8 in the order of about A to 1" in diameter. The liquid leaving the reaction chamber is passed to a receiver or collecting sump, from which the collected liquid can be again circulated or passed to "the reaction chamber. The recirculation of liquid to the reaction chamber is continued until the product in the receiver or collecting pump has the desired acid number. I

Thereafter, the process is discontinued in order to remove all of the product, and then the process is resumed with a fresh batch of alcohol or mixture of alcohols.

In this :process the amount of P 85 placed in the reaction.

In determining the amount or percentage of dithio phosphate acid ester in the product, a reasonable approximation is made on the basis of the acid number of the product. By knowing the composition of the alcohol or mixture of alcohols, the theoretical acid number of the dithiophosphate acid ester is calculated on the basis of .the following equation:

or (c) a mixture of one or more simple acids with one or more mixed acids. When the metal salt is desired, the salt-forming reagent can be the metal itself or compounds of the metal, for example, the oxides, hydroxides, carbonates, bicarbonates, sulfides, hydrosulfides, alcoholates, hydrides, etc. The hydroxides and oxides are preferred for the salt-forming reaction, because of their satisfactory reactivity, cheapness and availability; It is also contemplated in some instances to prepare a monovalent metal salt first and then to convert the same to the divalent metal salt by well-known double decomposition methods. However, it is preferred to use metal compounds which will react directly with the acid material to yeld the desired salt. 7

In preparing the metallic salts, inert diluents are generally used to facilitate subsequent processing operations such as filtration and for centrifugation. Specific examples of such diluents are conventionally refined and solvent-refined mineral lubricating oil fractions, orthod1'- chloro-benzene, alkylated diphenyl' ethers,l, alkylated naphthalenes, di-octyl phthalates, cetane, etc; Such diluents can be addedto the reaction mixture either prior to or after reaction of the acidmaterial with thesaltforming reagent. I

Below are two procedures whereby the salts of th s invention may be conveniently prepared. v

Procedure A.-One gram-mole of an acid material is mixed with 3% of its weight of methanol and a5 .to 25% excess of the selected salt-forming reagent. The mixture; is heated for about one hour at 50 to 70 C. at atmospheric pressure, and then for about 0. 5 hour at 100 C. under reduced pressure, e. g. 10to 100mm. Hg absolute pressure. Thereafter, a diluentmaterial may be added and the whole is filtered using Hyflo, a wellknown commercial siliceous filter-aid.

heated to -100 C. under reduced pressure, e. g. 50

to 200 mm. Hg absolute pressure, until distillation has substantially ceased. Thereafter, the material remaining in the flask is removed and filtered using Hyflo, a filter-aid.

The following tables provide specific examples of preparations of dithiophosphate acid esters which come within the scope of the present invention. It iS tO' be noted that the techniques used in prapai'ing the acid materials are. designated as the batch? and....circulatory? processes, and these processes are described hereinabove.

The methodsus'ed in preparing thejsalts are designated as Reaction ProceduresA and B" and these procedures hearing similar letters have been described above. Furthermore in Table V, the mineral oil used have the fined midcontinent pale .oil having a viscosity of about 100 Saybolt Universal seconds at 100 F. SSU-160 is solvent refined rnidcontinent oil having a viscosity of about 160 Saybolt Universal seconds at 100 F. SG-lOO following identities. SSU-100 is a conventionally re- 5 is an acid-treated Mid-Continent oil having a viscosity of about 100 Saybolt Universal seconds at 100 F.

T able III [Preparation of dithiophosphate acid esters containing mixed hydrocarbon radicals,'said acids produced by the reaction of phosphorus pentasulflde with an alcohol mixture containing two or more alcohols] Alcohol mixture employed Phosphorus Reaction condition 7 Product Ex. A1coho1(s) containing less Alcohol(s) containing at least pentasulfide No. than 6 carbon atoms 6 carbon atoms Tem- Con- Identity Gram- Grams Identity Gram- Grams Gram- Grams Hours pera- Fashion Grams Appearance Acid vermoles moles moles ture, numsion 0. bet value 1..-. Methanol... 3. 7 375.0 1, 124 4. 95 l, 100 2. 5 65 Citrcula- 1, 95-0 Dgrlidpurplo 155 91. 2

' ory. u 2...- .d 7.35 750.0 750 4. 95 1,100 2.5 75 d0. 1, 910 0 170 96.9 3..-- .-...d0 5. 563. 0 375 4. 95 l, 100 2. 5 75 d0 1, 980 Dark green 1 144 90. 7 Diisobutyl cy 2. 563 fluid. 7 clohexanol. 4 do 5.5 563.0 Cyclohexanol--- 3. 75 375 4. 95 1, 100 2. 5 -d0 1, 910 -d0 156 90.0 3,5,5-Trimethy1- 3. 86 563 hexanol. 5 Isopropanol. 3. 33 200. 0 Mlethyl-lcyclo- 1. 200 1. 27 283 4. 70-80 Batch... 011 do 195 84. 9

exano 6.--. do 3.25 195.8 do 1.14 130.5 1.0 222 2.0 501 ..do 265 100.0 7 do 2. 93 176.0 sec-Butanol 0.79 58. 8 1.0 222 2. 0 545 do 216 88.6 Methyl-cyolo- 0.52 68.8 hexanol. 8. d0..-. 3.38 202.8 .....d() 1.77 190.2 1.0 222 2.0 96 do 483 .do 216 92.0 9 Allyl alcohol. 1. 0 58. 0 4-me1t121yl-penta- 3.0 306 1. 0 222 3. 0 -100 do.. 444 Bfimivlu-green 161 80.5

no u 10-- --.d0 3.0 174. 0 do 3.0 306 1.5 333 20.0 90 .do..... 476 Ytjillltggv-brown 93 u *11.-. n-Butanol..- 9. 5 700. 0 9. 5 2, 100 5. 0 42-43 Gircula- 3, 400 Dark liquid--. 162 67.0

. Isobutanol. 28. 3 2, 100 tory. 12..- IsobutanoL- 3. 38 250.0 Methyl-cyclo- 2. 19 250 1. 39 310 4.0 00-100 Batch." 739 Dark green 177 92. 2

hexanol. fluid. 13." Sec-butane]- 1. 41 2. 74 312 1. 0 222 '1. 0 174 91. 5 1. 89 2. 28 260 1. 0 222 2. 0 177 91. 3 2. 11 2. 06 235. 2 1. 0 222 2. O 189 95. 5 2. 33 1. 211. 2 1. 0 222 2. 0 176 87. 3 3.38 2.19 250 1. 39 310 4.0 184 90. 2 2. 85 211. 2 .(1O 1. 52 172. 8 1. 0 222 2. 0 178 92. 5 12. 6 1, 125 4-Meltl21yl-penta- 11.0 1, 125 9.0 2, 000 2. 5 177 90.0

no Cyclohexanol- 7. 5 750 20 4-Me1tgyl-penta- 5. 15 5, 250 25. 3 5, 600 2. 0 94 do 10, 000 Dark 1iquid. 171 92.0 no

Oyclohexanol. 17. 5 1, 750

1 Conversion value not valid because of partial polymerization of the acid mass.

Table IV [Preparation of ditliiophosphate acid esters in which both at the hydrocarbon radicals are the same, said acids produced by the reaction of phosphorus pentasulfide with an alcohol] Alcohol employed Phosphorus Reaction conditions Product pentasulfide Example number Con- Identity Gram- Grams Gramgrams Hours Temp., Fashion Grams Appearance Acid vermoles moles 0. numsion ber value 21 'Isopropanol 6. 66 400 1. 68 370 4. 0 -100 Batch 686 Dark green fiuid 228 87. 5 22 do 100 6, 000 24. 8 5, 500 3. 0 55 Circulatory- 8, 000 Dark liquid 225 86. 1 23 d0. 6. 3 464 1. 0 222 4. 0 90-100 Batch 730 Dark green fluid. 198 85. 0 -24 do. 35. 40 2, 620 9.0 2, 000 4. 0 46-48 Circulatory- 3, 022 Dark liquid 186 80. 5 25 Sec-butanol- 8. 0 592 2. 0 444 6. 0 90-100 Batch 966 Dark green fluid- 203 S7. 9 26 do 189 14, 000 45. 0 10, 000 4. 5 43 Ciroulatory 18, 500 Black liquid. 185 80, 2 i 27 4-methy1-pentano1-2- .68. 50 7, 000 25. 2 5, 600 .i. 0 94 do 10, 000 Dark liquid- 170 90. 6 Methyl-cyclohexanol- 28. 00 3, 200 6. 85 1, 513 2. 0 100 o. 3, 961 Black liquid 174 99. 5 Octanol-Z 30. 80 4, 000 6.16 1, 370 4. 0 95-100 Batch 5, 117 Dark green fluid. 136 87. 0 3,5,5-trimethyl exanol. 17. 10 2, 500 9. 0 2, 000 4. 0 96-98 Circulatory 3, 030 .do 128 00. 0 5. 0 932 1. 0 222 2. 0 100 Batch 1, 012 Brown liquid 90 75. 0 4. 0 970 1. 0' a 222 4. 5 85-100 do 1, 068 Dark green 011. 85 87. 0

[Preparation of salts of dithiophosphate acid esters, in which salts a proportion of the hydrocarbon radicals present consist ofla) less than 6 carbon atoms, and (b) aliphatic and/or cycloaliphatic radicals having at least 6 carbon atoms.

"Table V f j A and B refer to the correspondingly identified procedures set forth in detail earlier in the specification] hatle radicals 559153 Under "Reaction rccedure the letters Dithiophosphate acid ester Mineral oil Salt-forming reagent Product Reac I I tion Per- Analysis Ex. Perpro cent No. Mole I cent cemin- Grams Appearance Y i Identity Grams per- Identity Grams Identity Grams molal dure eral prod-- (at room Per- Per- Peicent excess oil uct temperature) cent cent cent 1 1 pres- S 1 metal cut 33 Mixed acid of ex. 1.- 1, 200 SG100oil. 657 2110 159 15 A 33. 4 1, 527 Dgrlfigirown 13. 6 5. 70 6.15 34 Single acid of ex. 22-- 114 10 SSU-120 1, 116 ZnO 220 15 B 40. 2 2, 770 Liigli tdamber 5. 33

Single acid of ex. 27-- 1, 386 90 4 35 Single acid of ex. 22.- 400 10 N one. '.-i. ZnO 828 10 B 5, 835 ----.do 20. 1 9.42 9. 96

Single acid of ex. 27.. 4, 900 90 36 Single acid of ex. 22-- 114. 8 10 SSH-120, 1,145 ZnQ V 222 15 B 40.9 2, 800 ......do......... 5. 49

. o I Mixed acid of ex. 20. 1, 385.2 90 37 Single acid of ex. 22.. 472 40 SG-100 oil. 1, 244 ZnO' 233 15 B 42. 2 2, 151 do 12.85 5. 65 6.17

Single acid of ex. 24.- 151 10 Single acid of ex. 27.. 925 50 38 Single acid of ex. 22.. 472 40 do 1, 222 'ZnO 233 15 B 41. 4 2, 437 do 12.4 5. 78 6.32

Mixed acid of ex. 11. 173 10 Single acid of ex. 27.. 925 50 39 Single acid of ex. 22.. 472 40 .--do...--.. 1, 235 Z110 233 15 B 41. 8 2, 337 -....do..-.-.... 12. 9 5. 93 6. 42

Mixed acid of ex. 11. 345 20 Single acid of ex. 27.. 740 40 r 40 Single acid of ex. 22.. 472 40 do.....-. 1, 247 ZnO 233 15 B 42.2. 2,369 do 13.2 5. 90 6. 45

Mixed acid of ex. 11. 577 30 Single acid of ex. 27.- 555 30 41 Single acid of ex. 22.. 472 40 -..do.. 1, 348 ZnO 233 B 45. 6 2,245 ---..do....-.--. 12.4 5. 58 6.20

Single acid of ex. 24.. 602 40 Single acid of ex. 27.. 370 20 Y 42 Single acid of ex. 22.- 472 40. ---do 1, 260 ZnO 233 15 B 42. 6 2, 356 .....do 13. 5 5. 63 6. 32

Mixed acid of ex. 11. 690 40 Single acid of ex. 27.. 370 20 43 Single acid of ex. 22.. 472 40 ..-do 1, 382 ZnO 233 15 B 46.7 2,074, .....do 11.6 5.28 5. 78

Single acid of ex. 23.. 753 50 Single acid of ex. 27.. 185 10 44 Single acid of ex. 22.. 472 40 -.-do 1, 270 ZnO 233 15 B 43. 2,362 do.- 13.5 5. 67 6. 36

Mixed acid of ex. 11. 865 50 7 Single acid of ex. 27.. 185 10 Single acid of ex. 22.. 380 40 do.. 970 ZnO 187 15 B 41.0 1, 737 Amber fluid... 12. 5. 67 6.18 Single acid of ex. 27.. 888 60 I 46 Single acid of ex. 22-- 472 40 do... 1, 244 2110 233 15 B 42. 2 2, 395 .....do 12. 6 5. 71 6. 29

Single acid of ex. 26.. 151. 5 Y ,1 Single acid of ex. 27-. 925 50 l 47 Single acid of ex. 22-- 472 40 ---do 1, 278 ZnO 233 B 43. 3 2, 319 do 12. 2 5. 44 6.15

Single acid of ex. 26.. 303 Single acid of ex. 27-. 740 40 48 Single acid of ex. 22-- 472 40 ---d0-- 1, 311' Zn() 233 15 B 44. 5 2, 250 .....do 12. 6 5. 72 6. 31

Single acid of ex. 26.- 454. 5 Single acid of ex. 27.. 555 30 I y 49 Single acid of ex. 22.. 472 .do...- 1,545 ZnO 233 15 B 45.5 2,300 .do 12.4 5.81 6.26.

Single acid of ex. 26.- 646 40 Single acid of ex. 27.. 370 20 p 50 Single acid of ex. 22.- 424 .----do 990 ZnO 186 15 B 41.9 1, 941 .....do. 10. 2 5. 78 6. 32'

Single acid of ex. 27.- 816 55 51 Single acid of ex. 22.. 448 47. 5 ..d0- 996 Zn() 186 15 B 42.3 2, 015 ...--do. 12.5 5. 67 6. 23

Single acid of ex. 27.- 776 52. 5 52 Single acid of ex. 22-. 472 ----d0-. 1, 018 Z110 186 15 B 43. 2 2, 035 .....do 12. 4 5. 64 6. 23

Single acid of ex. 27.. 740 50 53 Mixed acid of ex. 5.. 610 None.-.-. ZnO 91 5 A 558 Brl-imwurlit-lgreen 23.2 10.6 11.3

r q 54 Single acid of ex. 22.. 496 52. 5 SG-100 oil. 1, 030 Z110 186' 15 B 43. 6 2, 009 Amber fluid-.. 11.2 5. 66 6. 38

Single acid of ex. 27.- 704 47. 5 55 Single acid of ex. 21.- 400 57. 5 None 2110 122 5 A 703 Brown-green 22. 9 11.0 10. 3

Single acid of ex. 28.. 400 42.5 quid. 56 Mixed acid of ex. 6-. 501 SSH-100 562 Z110 80.3 5 A 50.0 921 Green liquid-- o 57 Mixed acid of ex. 12- 739 I Z nO 100 5 A 686 Lilghlt11 lzirown 22. l 9. 93 9. 55

iq 58 Single acid of ex. 22.. 450 54 None ZnO 127 5 A 81 7 Bifiwgg-green 22. l 10. 1 9. 61

' u Single acid of ex. 28.. 450 46 r 59 Mixed acid of ex. 13- 347 ZnO 46 5 A 50 566 Green liquid. 9. 70 4.83 4. 54

60 Mixed acid of ex. 14- 558 ZnO 45;8 5 A 50 .980 .....do. 11.3 6. 37 61 Mixed acid of ex. 15. 573 Z110 82. 3 5 A 50' l, 111 Amber liquid. 9. 23 4. 46 4. 97 62 Mixed acid of ex. 16- 563 .ZnO '74. 7 5 A 50 1, 041 .....do 10.3 4. 5. 24 63 Mixed acid of ex. 17- 721 2110 101 5 A 631 Lilghitdbrown 21. 4 10.2 9. 70 u 64 Single acid of ex. 25.. 296 ZnO 5 A 565 -...do 21. 8 10. 1 9. 70

Single acid of ex. 28.- 296 j 65 Mixed acid of ex. 18. 567 Y 51815-160 626 ZnO, 76. 7 5 A 50 981 Cllearnrgd 10. 9 4.96 4. 86

' 0 q 66 Single acid of ex. 26.. 910 60 SG- oil. 1, 305 ZnO 233 15 B 44.2 2,212 Amber fluid... 11.4 5. 50 5. 93

Single acid of ex. 27.. 740 40 67 Single acid of ex. 26.. l, 060 .70 --.--d0- 1, 178 Z110. 233 15 B 40.0 2, 263 ..do 12. 5 5. 78 6. 25

Single acid of ex. 27.- 555 30 68 Single acid of ex. 26.. 1, 212 80 'do. 1, 211 ZnO 233 15 B 41. 0 2, 209 -....do.--.-... 12. 3 5.68 6. 09

Single acid of ex. 27.. 370 20 69 Mixed acid of ex. 19. 1, 200 None Ba(OH)1 378 5 r 'A 1, 550 Light green 16. 5 8. 10 17.0

s 1 70 Single acid of ex. 29.- 500 62. 5 SG-lOO oil. 807 01.10 131' 5 A '50. l, 530 Brown liquid. 7. 70 3. 70 6. 70

Single acid of ex. 25-. 200 37. 5 71 Single acid of ex. 30-. 500 61 ..-.-do.-. 721 iMgO 40 5v A 50 1, 342 Green liquid.- 8.20 4. 00 1. 50

Single acid of ex. 25-- 200 39 72 Single acid of ex. 31.. 500 52. 5 SSH- 729 Oa(0H)r 63 10 A 50 1, 348 Brown liquid- 6. 70 3. 10 2. 10

o Single acid of ex. 25.- 200 47. 5

asserts ii It will be noted that in the ditbiophosphate materials employed inExamples 37 to 42 inclusive, 45 to 52 inclusiv'e', 'etc., the ratio of carbon to phosphorus atoms is between 8:1 and 9.621. It will be further noted that in the dithiophosphate materials employed in Examples 43 and 44 the ratio of carbon to phosphorus atoms is 7.6:1.

The dithiophosphate materials of this invention are exceptionall ystable in mineral oils after standing for long periods of time. Stability as used herein means that the material does not become oil-insoluble either with or without undergoing chemical decomposition. Heretoj fore, it was believed that short chain length organic submaterial.

Table VI [Stability tests on zinc salts or dithiophosphate acid esters] Zincsalt of dithiophosphatc acid ester Stability of salt tested in an oven at 100 C. for a maximum of Prepared from a single alcohol; organic radical in said salt (40% SSU-100 Prepared from a plurality of alcohols, at least one of which contains 6 or more carbon atoms and at leastone of which contains less than 6 carbon atoms 15 days, observing appearance daily of a by volume blend of concentrate in Pennsylvania conventionally refined neutral oil having a Viscosity of about 150 Saybolt seconds at 100 F.

oil present to yield a concentrate) Organic radicals in said salt Blend Example No. of

salt Identity of radicals Mole Days Result percent Group I: V V

Isopropyl (Initially insoluble at test concentration) 4-mcthyl-pentyl-2 5 Heavy precipitate.

. 34 I50 ropyl Clear.

4-methyl-pentyl-2. 90 35 Isopropyl 10 15 Do.

4-methyl-pentyl-2 90 Isopropy 40 15 Do.

4-methyl-pentyl-2 60 I50 ropyl 45 15 Slight precipitate.

4-methyl-pentyl-2 51 Isoprdpyl 47. 5 15 Do.

4-methyl-pentyl-2 52. 5 7 52 Isopropyl 50 15 Do.

4-methyl-pentyl-2 50 Group II:

Isopropyl (Initially insoluble at test concentration) 4-methyl-pentyl-2 5 l Heavy precipitate. Cyclohexyl (Initially insoluble at test concentration) 36 Isopropyl 10 15 Clear.

4-n1ethyl-pentyl-2 2O Cyclohexyl Group III:

Isopropyl (Initially insoluble at test concentration) 4-methyl-pentyl-2 5 Heavy precipitate. Isobutyl 9 Do.

37 Isopropyl 40 15 Clear.

Isobutylr l0 4-methyl-pentyl-2 5O 43 Isopropy 40 15 D0.

Isobutyl; 50 4-1nethyl-pentyl-2 10 Group IV:

Isopropyl (Initially insoluble at test B t 1 1 Ic{0ncentration )t t nu y eavy precipi a e.

i t l t 2 a- -me y -pen y 15 Clear.

tyl- 22. 5 4-1nethyl-pentyl-2 3O 44 Isopi'opyl 40 15 Do nutyL. 12.5 Isobutyl 37. 5 4-methyl-pentyl-2 10 Group V:

Isopropyl (Initially insoluble at test concentration) IsobutyL- V 9 Heavy precipitate. 4-methyl-pentyl-2 5 Do.

41v Isopropyl 40 15 Clear.

Isobutyl 40 4-methyl-pentyl-2 20 assess;

Table VI Cont1nued Zinc salt of dithiophosphate acid ester Stability of salt tested in an oven at 100 0. for a maximum of I W 15 days, observing appearance Prepared irom a plurality or alcohols, at least daily of a 5% by volume blend one of which contains 6 or more carbon of concentrate in Pennsylvania atoms and at least one of which contains conventionally refined neutral. Prepared from a single alless than 6 carbon atoms oilhaving a viscosity of about .cohol; organic radical n I 150 Saybolt seconds at 100 F. said salt (40% SSU-lOO Oil present to yield a i concentrate) Organic radicals in said salt Blend Example No. of

salt Identity of radicals Mole. Days Result percent w Group VI:

Isopropyl (Initially insoluble at test concentration) Sec-buty 15 Heavy precipitate 4-methyl-pentyl-2 5 I Do." I

46 Isopropyl 40 15 Clear.

Sec-bntyl l 4-methyl-penty 50 IsopropyL- 40 15 Slight precipitate. Sec-butyl 20 4-methyl-penty 40 Isopropyl- 40V 15 Do. i iii-"r 28 -me y en y Group VII: p

Sec-butyl 15 Do. 4-methyl-pentyl- Do.

66 Sec-butyl 60 Clear.

4-methyl-pentyl-2 40 68 Sec-butyl 80 15 Do,

. 4-methyl-pentyl-2 Table VII [Solubility tests on zinc salts of dithiophosphate acid esters.]

Zinc salt of dithiophosphate acid esters Solubility of salt in Pennsylvania conventionallyrefined neutral oil having a viscosity 0! about 150 Saybolt sec- Prepared from a plurality of alcohols, ends at 100 F.; percent of concentrate tested and apat least one of which contains 6 or pearance of the oil solution after l'month storage at more carbon atoms and at least one room temperature v 4 Prepared from a single of which contains less than 6 carbo l alcohol; organic radical atoms in said salt SSU- 100 011 present to yield a concentrate) Organic radicals in said salt 7 Exlglmple 507 107 "7 0. o o 1 u of salt Identity of radicals Mole I percent Group I:

Seg-butyL Precipitated-.- Precipitated Precipitated. Methyl-cyclohexyl. Clear 1 do Do.

59 Sec-butyl. 34 do Clear Clear. Methyl-cyclohexyl 66 v 60 Sec-butyL =45, do o Slight sediment.. 1

Methyl-cyclohexyl.- 55 61 Sec-butyl; 50.5 do do Clear.

Methyl-cyclohexyl. 49. 5 62 Sec-butyl 56 do do Do. Methyl-cyclohexyl 44 Y I 65 Sec- 11 65 .--do do Do.

Methyl-cyclohexyl. 35 I Group II: 1 1

Isopropyl- (Initial.y insoluble at test concentration) Methyl-cyclohexyl Precipitated. Precipitated.

53 Isopropyl 65 Slight sediment Clear.

Methyl-cyclohexyl 35 I p The above data clearly indicates that the novel dithio of at least six carbon atoms. Generally, the aliphatic hydrocarbon radicals can be present in amounts as high as 90% and as low as 10%, more usually materials containing such radicals in amounts of about 30 to 50% will be found. In such situations the remainder of the radicals contain at least six carbon'atoms" and are selected from the group consisting of alip hatic and cycloaliphatic hydrocarbon radicals.

my novel dithiophosphate salt-ester materials in mineral oi1s, it was-discovered that such materials are at least as eifective as corrosion inhibitors in lubricants when employing lesser amounts on a weight basis than those materials in which all the hydrocarbon substituents are at least sixf carbon atoms. This unusual property of my novel materials is illustrated by the data givcninethelta ble below. T he-test samples were investigated in a Chevrolet c dcscri bcdinpo- ZCRC engine'.-in accordance with .the procedur ed-u rdinatin Research Council Test P 545; May 1945.

In addition to the unexpected finding of the stability ofa Table VIII Chevrolet. engine test X- Composition average No. mg. loss per whole bearing SAE 30 solvent extracted midcontincnt base oill viscosity index of 95. plus: fg

0.95 weight percent 01' Example N o. 45 in Table V SAE 30 solvent extracted midcontinent basc oil- 2 viscosity index of 95, plus: 8.

0.92 weight percent of Example No. 68 in Table V SAE 30 solvent extracted midcontinent base oil- 3 viscosity index of 95, plus: r r 35, rcpeat 1.07 weight percent zinc di-(4-mcthy1-pentyl-2) ditest 41.

thiophosphate. V SAE 30 solvent extracted midcontinent base oil 4 viscosity index of 85, plus: 47. 0.53 weight percent of Example N0. 45 in Table V; SAE 30 solvent extracted midcontincnt oil-vis-' cosity index 85 plus: 0.67 weight percent of zinc dithiophosphate acid 5 ester derived from mixed dithiophosphate'acid 122 ester which is prepared by reacting 4 moles of mixture of equal parts by weight of methylcyclohexanol and capryl alcohol with 1 mole of 4 PzSs at 100 C. for 4 hours.

Considering Examples 4 and 5 in Table VIII, wherein the same base oil was employed, it can be seen that 24.5% more of dithiophosphate salt-ester was used in ExampleS than in Example 4, but still, the dithiophosphate salt-ester material of this invention is more eifectivethanthe prior art material with respect to corrosion inhibition. On the other hand, when comparing Examples 1, 2 and 3, in which the same base oil was used, 12.5% more dithiophosphate salt-ester was used in Example 3 than in Example 1; whereas 16.3% more dithiophosphate salt-ester was used in Example 3 than in Example 2. Notwithstanding the use of greater quantities of dithiophosphate salt-esterscontaining only radicals of at least six' carbon atoms, the corrosion inhibiting effect thereof is less than what is obtained With the dithiophosphatc saltecsters produced in accordance with the present invention.-

As noted above, the novel 'dithiophosphate salt-esters of" this invention are useful in lubricating oils. However, it should be understood that my novel materials can be used for a variety of purposes such as for example in crankcase oils, torque-converter oils, gear oils, turbine oils, turbo-jet oils, cutting oils, rolling mill lubricants, rock-drilling lubricants, greases, etc; as well as for non-lubricating purposes 6. g. transformer oils, hydraulic oils, plastics, flotation agents, hydrocarbon fuels such as gasoline, fuel oil, furnace oil, etc. Generally, the novel dithiophosphate saltcstcr materials of this invention will find use in lubricating oils in amounts of from about 0.05 to more usually from about 0.1 to 7.5% and preferably from about 0.2 to 5%, based on the weight of the oil.

In the light of the foregoing description of myinvcntion as broadly defined and as illustrated by specific examples, it will be noted that the novel product which I have produced may be defined as an oil-soluble organic dithiophos- Other modes of applying the principle of the invention may be employed, change being made as regards the details described, provided the features stated in any of the following claims, or the equivalent of such, be employed.

I therefore particularly point out and distinctly claim as my invention:

1.' As a composition of matter the oil-soluble group II metal salts of a mixture of simple di-esters of dithiophosphoric acids, one of said di-esters having the formula R0 SH where R is selected from the group consisting of saturated aliphatic and cycloaliphatic radicals having less than six carbon atoms, and another of said di-estcrs having the formula R'O/ \SH where R is selected from the group consisting of saturated aliphatic and cycloaliphatic radicals having at least phatc material, in which material there is presenta sub- H stantial proportion of each of: (1) aliphatic radicals having less than six carbon atoms, and (2) organic radicals having at least six carbon atoms and selected from the class consisting of aliphatic and cycloaliphatic radicals and in which material all of said radicalspresent are derived from organic hydroxyl bodies having an ionization constant less than .1 x 10- at 25 C. l .f

For certain uses, and particularly as lubricant additives,

superior results have usually been obtained when the salt-forming radical employed in the preparation of dithiophosphatc salt-ester materials of the present invention is selected from the metals in group II of the periodic table of elements, and especially where the salt-forming radical'is zinc. Further, it has been found that dithiophosphate matcrials'which have an average of from 8 to 9.6

preferable for many uses.

six carbon atoms, said mixture of simple di-esters being characterized in that the ratio of carbon atoms to phosphorus atoms in said mixture is within the range of about 7.6:1 to about 9.6:1.

2. The group II metal salts of claim 1 characterized further in that the saturated alcoh ols are alkanols.

3. The group II metal salts of claim 1 characterized further in that the saturated alcohol having less than six carbon atoms is a propyl alcohol.

4. The group II divalent metal salts of claim 1 characterized further in that the saturated alcohol having at leastsix carbon atoms is a hexyl alcohol.

5. The group II divalent metal salts of claim 1 charactcrized further in that the saturated alcohol having less than six carbon atoms is isopropyl alcohol and the saturated alcohol having at least six carbon atoms is 4-methyl- I pentanol-2.

6. The group II divalcntrnetal salts of claim 1 characterized further in that the divalent metal is zinc.

7. "The group II divalent metal salts of claim 1 characterized further in that the saturated alcohol is an alkanol and the group II divalent metal is zinc.

8. The zinc salts of claim 7 characterized further in that the alkanol having less than six carbon atoms is isopropyl alcohol and the alkanol having at least six about 9.621.

10. As a composition of matter the oil-soluble group II metal salts of a mixture of three di-esters of dithiophosphoric acids, and of said di-cstcrs having the formula where R is selected from the group consisting of saturated aliphatic and cycloaliphatic radicals having less than 6 carbon atoms, the second of said diesters having the formula R'O/ SH where R is selected from the group consisting of saturated aliphatic and cycloaliphatic radicals having at least 6 carbon atoms, and the third of said di-estershaving the formula R'O SH 17 said mixture of di-esters being characterized in that the ratio of carbon atoms to phosphorus atoms in said mixture is within the range of about 7.621 to about 9.6:1.

11. As a composition of matter the oil-soluble group II metal salts of a mixture of di-esters of dithiophosphoric acids, one of said di-esters having the formula where R is selected from the group consisting of saturated aliphatic and cycloaliphatic radicals having at least 6 carbon atoms, and the third of said di-esters having the formula said mixture of di-esters being characterized in that the ratio of carbon atoms to phosphorus atoms in said mixture is within the range of about 7.611 to about 9.6:1, said mixture of di-esters being further characterized in that at least 50% of the mixture consists of simple di-esters.

References Cited in the file of this patent UNITED STATES PATENTS 2,370,080 Schreiber Feb. 20, 1945 2,373,811 Cook Apr. 17, 1945 2,387,538 Smith Oct. 23, 1945 2,501,731 Mertes Mar. 28, 1950 2,579,037 Evans Dec. 18, 1951 2,579,038 Evans Dec. 18, 1951 2,680,123 Mulvany June 1, 1954 

1. AS A COMPOSITION OF MATTER THE OIL-SOLUBLE GROUP II METAL SALTS OF A MIXTURE OF SIMPLE DI-ESTERS OF DITHIOPHOSPHORIC ACIDS, ONE OF SAID DI-ESTERS HAVING THE FORMULA 